The surface of the fiber optic humidity sensor is a layered structure composed of silicon oxide and zirconia with different reflection coefficients. Through advanced thermal curing technology, the pore size of the sensor surface is controlled at 0.3nm, and water molecules at 0.28nm can penetrate. The controller emits a beam of near-infrared light at 790-820nm, which is transmitted to the sensor through a fiber optic cable. The water molecules entering the sensor will change the reflection coefficient of the light, causing a change in wavelength, which is proportional to the moisture content of the medium.

In addition, there is an infrared moisture meter that uses physical heating to remove free moisture and measures moisture through weight changes. This type of moisture meter is often used in industries with low precision requirements, such as pharmaceuticals, plastics, chemicals, food, grains, etc. Because compared to an oven, the testing time is shorter, the use is convenient, the accuracy is higher, and the efficiency is much higher, usually only a few minutes.